Bonnie Slotnick Cookbooks has a strong 20th-century collection (163 W. 10th St., New York, NY; 212-989-8962).
Cook Books by Janet Jarvits is a prime source for vintage community cookbooks published in California (1388 E. Washington Blvd., Pasadena, CA; 626-296-1638 or www.cookbookjj.com).
The Wine and Food Library, run by Jan Longone, carries publications that date as far back as the 1870s (1207 W. Madison St., Ann Arbor, MI; 313-663-4894).